A discharge unit (20) includes an insulating member (41) which supports a discharge electrode (70) and a counter electrode (60). The insulating member (41) has a base (44) on a periphery of which the counter electrode (60) is supported, a recess (46) formed in the base (44) and recessed in a direction intersecting with the flow of air flowing through an air passage (27), and a support (47) which extends from a bottom of the recess (46) to protrude outward from an open end of the recess (46) and which supports the discharge electrode (70).
